The Mustang really has nothing to give up for the project. You don't have a frame, a rear axle that will be big enough, and the front suspension will only yield a few small pieces.

The aftermarket should have some kits available to install a modern rear axle under the Merc frame, maybe a widened Mustang ll style front suspension that's designed for this body, and engine and trans mounts for the 350/350 setup.

This is a major project, and if I may be frank, it sounds like you are somewhat new to this game. I would find a car that does not need major surgery, but can simply be modified a little at a time. Probably a 50s or 60s G.M. car that your engine can simply bolt into. Good luck.